The tragic skiing accident suffered by the Formula 1 racing champion Michael Schumacher has dominated the headlines in recent days - not least because he remains in a serious condition in a medically induced coma ...

The tragic skiing accident suffered by the Formula 1 racing champion Michael Schumacher has dominated the headlines in recent days - not least because he remains in a serious condition in a medically induced coma. It is by no means certain that he will survive, and completely unknown how severely he will be affected in the long term if he does.

Since his accident much of the discussion has centred (as it did after the actress Natasha Richardson died in 2009 after a skiing fall) on whether his ski helmet protected him. While neurosurgeons have argued he would have been dead already without it, he has still sustained serious head injuries. The helmet may have reduced the effect of the direct impact on his skull when he hit his head on a rock. It may have acted as a shock absorber, but it could not stop his brain being shaken around inside his skull, causing bleeding into the brain, bruising and swelling.

As far as skiing is concerned, there are relatively few studies on the impact of helmet wearing on the likelihood of severe head injury in a fall. A major study from the early '90s suggested that ski helmets could reduce the risk of head injuries by 50%. (1) However, fears have been raised that wearing a ski helmet might actually increase the risk of injuries to the cervical (neck) spine, which can cause paralysis or death. (2) In young people at least, there is no evidence that this fear is borne out. (2)

While some of us may be contemplating heading off on ski trips in the next few weeks, far more of us are cyclists, and the debate over helmet wearing for cyclists is heated. That cyclists are more vulnerable to head injuries than people travelling by car is undisputed - they are more than twice as likely to be killed and 10 times as likely to be injured for every kilometre they travel, and head injuries account for one in three cycle-related hospital admissions and three in four deaths. (3) At first sight, it makes perfect sense that wearing a helmet, which has been shown to protect children against cycling head injuries, (4) should be compulsory for adults as well.

A recent analysis of the impact of compulsory cycle helmet laws in Canada shows a reduction of 26% in the rate of head injuries in provinces and territories where the laws were enforced compared to provinces where the status quo remained. (3) But interpreting the data is complicated by a host of other factors. Admission rates were going down before the legislation was introduced and once the law was in place, fewer people cycled. The 'pro-choice lobbyists' have argued that this makes any conclusions about a direct effect of helmet wearing impossible. However, another study showed that once the legislation came in, head injuries among cyclists dropped more than limb injuries, suggesting that helmets were offering protection. (5) The respected Cochrane Collaboration, which is renowned in medical circles for analysing all the evidence and coming up with really reliable findings, is completely convinced, and tackles the critics head on. Their summary? 'Helmets reduce bicycle-related head and facial injuries for bicyclists of all ages involved in all types of crashes, including those involving motor vehicles. Our response to comments from critics is presented in the Feedback section.' (6)

Some cyclists object on the grounds of infringement of their personal liberty. Perhaps the personal liberty argument is best countered by someone who knows all about head injuries - Beverley Turner, the wife of Olympic gold medallist James Cracknell, who nearly died when he was struck from behind by a truck while cycling. Her view on this version of freedom? "I promise you if 'personal liberty' matters to you, not being able to take yourself to the lavatory on waking will come as a real shock."

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.